Marking machines of the type with which the control system of the present invention is particularly useful typically includes a surface or table to hold and position a workpiece to be imprinted, and a marking member having a plurality of symbols thereon which can be positioned to mark the workpiece in a sequential pattern of selected symbols. Typically, this marking member may be changed to provide different desired combinations and sizes of characters or symbols.
In such marking machines, the marking member has been operated in response to actuation of a typewriter-like keyboard and electromechanical devices associated therewith. In operation, a character or symbol is selected by actuating or depressing one of the keys on the keyboard which corresponds to the character or symbol desired to be marked. The marking member then is indexed to locate the selected character or symbol in a marking position. The marking member is subsequently displaced into engagement with the workpiece to thereby mark or print onto the workpiece the selected character or symbol. Typically, the workpiece is then advanced a selected distance to locate the workpiece in position to be imprinted or marked with the next selected character or symbol.
In U.S. Pat. Nos. 3,924,720 and 3,945,479, assigned to the assignee of this application, there is disclosed such an electromechanically controlled marking machine designed for imprinting at relatively high speeds. The machine disclosed in the above-referenced patents includes a frame and a marking ram carrying a marking member or wheel which is slidably mounted on the frame and driven by an electric motor. This marking wheel is rotated to position the characters or symbols on the periphery thereof in position for marking a workpiece disposed therebelow and is transversely displaced to effect the desired marking of the workpiece.
In U.S. Pat. No. 4,071,131, also assigned to the assignee of this application, there is disclosed an electronic control system for the type of marking machines disclosed in the first cited patents which improve the reliability, performance and operational control of those machines and replaced electromechanical devices which limit the speed and reliability of operation with an electronic control circuit. All of the above cited patents and the disclosures therein are incorporated herein by reference in order to minimize the necessity of describing in detail what is contained therein.
While the marking machines and the operation thereof under control of the electronic control system disclosed in said U.S. Pat. No. 4,071,131, did in fact result in improved reliability and less electromechanical wear, there still were a number of mechanical components necessary in order to operate the machine. In addition, while the control system in the aforementioned U.S. Pat. No. 4,071,131 did improve the operational speed of such marking machines significantly, the need for faster operation remained as well as additional operational flexibility and even better reliability.